1. Field of the Invention
The Present invention relates to a method of removing contaminating impurities from used battery acid fluid so to permit the fluid to be used in new batteries or concentrated for sale. More specifically, the method employs a series of filtration and extraction steps to regenerate used battery acid fluid by removing diluting contaminants, including iron and antimony.
2. Description of the Prior Art
A serious problem, both economically and environmentally, in the manufacture and sale of lead-acid batteries is how to handle and dispose of contaminated battery acid fluid contained in discarded batteries. Until relatively recent environmental regulations ended the practice, this waste, comprising sulfuric acid (H.sub.2 SO.sub.4) diluted with various metal and non-meta contaminants, traditionally has been dumped in landfills or flushed into public sewers. The advent of severe pollution Penalties has ended this practice, but, until now, no reasonable alternative plan of disposal has been developed.
Presently, battery acid fluid from trade-in batteries is handled in a number of less than ideal manners. Some manufacturers have found an outlet through industries with demand for dilute sulfuric acid. However, this places the battery manufacturers at the mercy of the demands of other markets, and presents a whole host of problems when faced with the advent of cradle-to-grave environmental laws. Other manufacturers have paid to have the battery acid fluid neutralized and then disposed of in certain restricted landfills. This can be very expensive and is needlessly wasteful.
In the course of developing the present invention, the inventor encountered a number of proposals for reclamation of battery acid fluid. One solution proposed was distilling the sulfuric acid via indirect heat in closed vessels under vacuum. This was dismissed as unreasonable in light of high energy costs, high investment costs, serious corrosion and disposal Problems, and environmental concerns. Another solution proposed was acid retardation in the form of an ion exchange process entailing passing a strong acid feed through a strong base ion exchange resin. Once again this proposal proved unreasonably expensive in investment and development costs. A further proposal was to remove contaminants through electrolytic processing. Despite early promising results using this method, further tests demonstrated that iron removal was insufficient for commercial purposes.
In light of the foregoing, it is a primary object of the present invention to avoid the waste and expense of disposal of contaminated battery acid fluid by providing a method of reclaiming contaminated battery acid fluid for use in new batteries or for concentration for resale.
Another object of the present invention is to provide a method of battery acid fluid reclamation which is commercially practical, requires minimal capital investment, is relatively inexpensive to operate, and minimizes environmental risk.